Terminal deoxynucleotidyl transferase (TdT) is a non-template-dependent DNA polymerase that catalyzes the repeated addition of deoxynucleotides to the 3' hydroxyl end of a DNA molecule (double-stranded/single-stranded DNA or oligonucleotide chain). The shortest length of oligonucleotides that can be catalyzed is 3 nucleotides. When the template is an RNA strand, the eventual catalytic activity of TdT depends on the nucleotide characteristics and advanced structure of template 3', but in general, the synthesis effect under the RNA template is lower than that of the DNA template.

This kit is commonly used for the synthesis of homopolymers and heteromers, linearized double-stranded DNA 3'-OH-terminal homopolymer tailing, oligodeoxynucleotides, and DNA markers (e.g., ddNTP, DIG-dUTP, fluorescein-12-dutp, etc.), 5'-RACE (rapid amplification of cDNA terminals) and in situ localization of apoptosis, etc.